This invention relates to a preservative for digestible food products that is made from substances that are currently used in food products and generally recognized as safe. The base ingredient of this preservative is cellulose which is an indigestible carbohydrate composed of carbon, hydrogen and oxygen. The chemical terminology for this natural polymer is beta-1,4-glucan. Due to the atomic arrangements at its glycosidic bonds, the bonds linking the basic units, cellulose is insoluble in water. For all practical purposes, cellulose is considered non-caloric and is considered a GRAS (generally recognized as safe) substance by the FDA. Cellulose is the principal structural component of plants and is the most abundant source of complex carbohydrates in the world. To obtain pure cellulose, this component is progressively extracted and purified from plants. During the entire extraction process, the cellulose is not dissolved. Therefore, it exists in a naturally fibrous form and exhibits characteristics common to all fibers. The length of cellulose fibers is dependent upon the extraction process, while the typical width (diameter) of cellulose fiber is approximately 15-25 microns. Powdered cellulose is currently used in the food industry as a high fiber source and/or a non-caloric bulking agent.
Most paper is made from plant fiber, most often wood, in a process that separates the cellulose from the other plant fiber material. Cellulose is the major constituent of plant fibers. Carbohydrates, including cellulose are convertible into glucose by hydrolysis, a chemical process of decomposition. Under appropriate conditions the bacteria present in the paper making process contribute to and hasten decomposition. As a result, when cellulose pulp material is maintained in a hydrous state it has a very short shelf life.
In the paper making industry biocides are added to the slurry in the pulper. A pulper is basically a vat for receiving a material that can be agitated by mechanical means and includes means for controlling the temperature. The biocides slow the deterioration of the hydrous cellulose pulp material but do not stop it. The biocides that are added to the slurry in the pulper are poisonous and thus the hydrous cellulose pulp material can not be used in many consumer products especially products intended for human consumption. Thus, not only are the biocides not effective, they are poisonous and therefore present a hazard. In the paper making process, the water is driven from the cellulose pulp and the remaining fiber is dried in a continuous operation. After the water has been removed, decomposition of the cellulose pulp ceases. However, if the process is suspended with the cellulose pulp in the hydrous state, for example over 90% water, the pulp has a very short shelf life. This short shelf life has been a major obstacle to the development of non-paper industry uses for hydrous cellulose pulp. Generally speaking, hydrous cellulose pulp is vulnerable to decomposition regardless of whether the pulp is derived from virgin vegetable constituents or from paper in a recycling operation.
Waxed paper is customarily manufactured by forming the paper sheet first then treating the sheet with an application of wax coating, either in dry or liquid form. For example, molten paraffin wax is easily applied by continuously passing a paper sheet through a molten bath of wax, removing the excess and then chilling. Such waxed papers have excellent resistance to water vapor, are free from odor, taste and toxicity and are low in cost.
At one time, waste or new waxed paper presented problems in the paper recycling industry. When waste or new wax paper was recycled waxy spots would appear on the resulting recycled paper and a wax coating would collect on the equipment thus fouling the recycling process. Consequently, the resulting recycled paper was considered inferior and it was often necessary to stop the process so that the equipment could be adequately cleaned.
This problem with recycling waste or new waxed paper was solved, however, by adding water dispersible non-ionic emulsifiers to the pulper during the repulping phase of the recycling process. The mixture containing the emulsifier is mechanically agitated at a temperature sufficiently high to melt the wax, for example from approximately 135.degree. to 190.degree. Fahrenheit. This process produced an emulsified wax-fiber slurry having a solids consistency of approximately 20% by weight. The hydrous cellulose pulp produced in this process for recycling waste or new waxed paper has the property of an unlimited shelf life. U.S. Pat. Nos. 3,808,089 and 3,822,178, the disclosures of which are incorporated herein by reference, fully disclose the above described process.
Various non-paper industry uses have been discovered for this hydrous cellulose pulp having an unlimited shelf life. For example, as a dispersed ingredient in toothpaste, shampoo, soap, detergent, lotions and cream products. Other non-paper industry uses that were discovered for this product were its use as artificial snow and mulch. The discovery of these non-paper industry uses of hydrous cellulose pulp having an unlimited shelf life is the subject matter of U.S. Pat. No. 5,412,090 that issued on May 2, 1995. U.S. Pat. No. 5,412,090 is hereby incorporated by reference as a part of this application. The hydrous cellulose pulp having an unlimited shelf life produced in accordance with the disclosure of U.S. Pat. No. 5,412,090 has a fiber content of about 4-6% by weight and has a fiber length of approximately 2,000 microns.
Powdered cellulose is used throughout the food industry for various functional purposes. It is the only dietary fiber used in the food industry. For example dietary fibers serve as a non caloric-bulking agent in numerous food products. Powdered cellulose is the standard caking agent used in the dairy industry to prevent caking and clumping of grated cheese, and more recently has gained popularity in dry seasoning, spiced soups and other mixtures. Powdered cellulose also improve the flowability of products, which enhances performance when packaging the product. However, as currently used in the food industry, powdered cellulose does not have a preservative attribute.
It was found that when hydrous cellulose pulp, produced in accordance with the disclosure of U.S. Pat. No. 5,412,090, is used in shampoo as a scrubbing agent, traces of fiber are left on the hair. These fibers are large enough to be visible to the consumer. This residue, although harmless, was found to be unacceptable to some consumers. It was found that if the hydrous cellulose pulp, formed in accordance with U.S. Pat. No. 5,412,090, is filtered, for example through a 2 micrometer filter, the non-toxic filtrate contains only about 0.67% hydrous cellulose pulp by weight. This hydrous cellulose is in the form of colloidal fibers and fibers that are a maximum of 10 microns in length. This filtrate retains the quality of an unlimited shelf life. However, the filtrate, like the fiber, is white in color. This was the result of some of the white wax remaining in the water phase of the filtrate. This process has been improved such that all of the wax is either on the fiber or emulsified. The colloidal fibers contained in the filtrate are transparent and thus are not, under any condition, visible to the naked eye.
Many consumer products are formed with a water base. The purest natural water includes microorganisms that will in time cause water base products to become rancid if preservatives are not added. Thus, water based consumer products commonly include a preservative. Although preservatives are chosen that most people can tolerate, some individuals are allergic to or have reactions to these preservatives. Also, the long range effect of these preservatives is often not known for certain.
A food grade preservative commonly identified as potassium sorbate and technically identified as 2,4 Hexadienoic Acid is used for example as a preservative for food products such as pickles. Potassium sorbate is commercially available in the form of a dry powder that can be placed in solution with a water based ingredient. When potassium sorbate is added to the above discussed hydrous cellulose pulp produced in accordance with the disclosure of U.S. Pat. No. 5,412,090 or its non-toxic filtrate an excellent water based preservative for consumer products is obtained. This combination of potassium sorbate and the non toxic filtrate is the subject matter of co-pending application Ser. No. 08/807,426, filed on Feb. 28, 1997. The subject matter of co-pending applications Ser. Nos. 08/808,212 and 08/807,426 are hereby included by reference as a part of this application.
There is a need for a powdered cellulose that acts as a preservative that can be used in the food industry.
There is also a need for a preservative that can be added to food products, intended for human consumption, that is made from natural ingredients that are safe and digestible.
Furthermore, there is a need for a water base that can be used for food products, made from natural digestible ingredients, that functions as a food preservative and is not visible to the naked eye.
Still further there is a need for a digestible food preservative that can be applied to the external surfaces of fresh fruits and vegetables that will extend the time that fresh fruits and vegetables can be stored in an un-refrigerated state.